Hypothyroidism as a protective factor in acute stroke patients.

OBJECTIVE: It has been reported that hypothyroidism is associated with better survival in elderly persons. We investigated possible associations of thyroid status with clinical outcome in patients with acute stroke.

DESIGN: Retrospective analysis.

PATIENTS: Consecutive patients (median age 70 years) admitted for acute stroke.

MEASUREMENTS: Total T3, T4 and TSH levels. Stroke severity evaluation using the Scandinavian Stroke Scale (SSS) and the Glasgow Coma Score (GCS). Handicap and survival assessment over 12 months.

RESULTS: Of 744 patients where thyroid function tests were available within the first 24 h of stroke, 13 had elevated TSH (>or= 10 microU/ml; range 10-42 microU/ml) (hypo-group), 51 had mildly elevated TSH (3.3-9.9 microU/ml) and 680 had nonelevated TSH < 3.3 microU/ml. In the hypo-group transient ischaemic attacks (TIA's) were more prevalent (46.2%) compared to the groups of mildly elevated TSH (11.8%) and nonelevated TSH (12.4%, P < 0.002). Hypo-group had more frequently an adequate level of consciousness (GCS 14-15 = fully alert): 92.3%vs 74.5% and 63.7% (P = 0.033), a milder neurological deficit (SSS score 45-58) 76.9%vs 39.2% and 38.7% (P = 0.02) compared to the other two groups, respectively, and a tendency for lower glucose levels on admission. One year outcome tended to be better with respect to survival and handicap.

CONCLUSIONS: Acute stroke patients with laboratory findings compatible with pre-existing hypothyroidism on admission, appear to have better clinical presentation and outcome; we speculate that a reduced response to stress and previous TIA's, possibly related to endogenous 'preconditioning', may contribute to this phenomenon.